Yes. Ground must be shared between all circuits, just be sure never to share VCC. I suppose you could, theoretically, make separate circuits with optoisolators, but for what we are doing that makes no sense. I have had no problems sharing ground between all of my circuits, just keep the high voltage separate from low voltage through transistors, driver circuits, whatever.

Edit:oops, didn't see there was another page. Glad you figured it out. As you can see from my schematic (I think I posted that here) I'm just driving a bunch of MPSA42s from a shift register.

Progress report:I've set up four 74141s and two shift registers (595s), but am running two nixies so far, and a bulb.I'm using a spare PC PSU for power, the arduino is the one I fried so it needs to be powered from USB. I'll be adding a USB plug to the PSU as soon as I've been to maplin to buy a male type B plug.

Here's some pics:Nixies:Click for Big.

The rig (using a bit of Meccano to make a gantry to hold the nixies):

Top view:

At the top is the 12v - 180v PSU.Coming in on the right is a 5v line and a 12v line from the PSU.The breadboard is 74141, 74141 and 595 (in use) and the same again waiting to be hooked up and an IN-35 bulb.The arduino is sat on a bit of polystyrene and attached to the gantry. The nixies are in sockets suspended from the gantry.

I am getting a bit confused.You guys said that optocouplers are not necessary if I am going to multiplex the nixies.In your setup aren't necessary because you hook up the anode and use a 74hc595 with two 74141 for 2 nixies. So if you have 6 nixies you have 3 595 and 6 74141, at least.

But, if you, for example, connect all the cathodes of your nixies together to a single 74141 you need to switch the anodes with the 595, in high voltage multiplexing them and using persistence of vision. I supposed that this was the meaning of the transistor, for dividing the high voltage of the nixies from the low voltage of the IC's and the arduino...

wyager

Wow-lots of wires! Thankfully, the IN-14s I'm using (as soon as USPS feels like delivering them, they've been in the US since at least the 26th) come with long leads, so hopefully it will just be plug-and-play.

Wow-lots of wires! Thankfully, the IN-14s I'm using (as soon as USPS feels like delivering them, they've been in the US since at least the 26th) come with long leads, so hopefully it will just be plug-and-play.

Cool. I had to solder leads onto the sockets. There's four 74141s and two 595s on my breadboard. I'm slightly amazed I got it all working pretty much first time (I'd got digits 8 and 9 mixed up on one of the nixies). It'd have all been easier if I could make my own PCBs but that's something I've not got round to yet.